i) Field of the Invention
This invention relates to novel polymers having N-phthalazone and ether linkages and their preparation; the invention also relates to certain novel phthalazones useful in the manufacture of the polymers, and their preparation; the invention also relates to certain novel substituted phenolphthaleins and hydroxybenzoylbenzoic acids, and processes for producing them, which are useful in an economic route for the manufacture of the polymers; the invention also relates to a process for producing valuable substituted 4-aminophenols, and to novel substituted 4-aminophenols.
ii) Brief Description of Prior Art
Phenolphthalein is readily synthesized from phthalic anhydride and phenol in the presence of a strong acid catalyst. It has been used principally as a laxative and as a chemical indicator since in the presence of base it turns deep red.
The reaction is illustrated by the following scheme: ##STR2##
Polymers have been synthesized from phenolphthalein including polyesters, polycarbonates and poly(ether ketone)s, and they generally have high glass transition temperatures. For example, Morgan (P. Morgan, J. Pol. Sci. A2, 437 (1964)) synthesized polyesters and polycarbonates from phenolphthalein. However, because the molecule is not symmetrical the polymers are amorphous, and problems often arise in the synthesis of these polymers as well as in the processing of the materials because of reactions involving the lactone ring. A poly(ether ketone) has been synthesized from phenolphthalein (G. Qipeng, H. Jinyu & C. Tianlu, J. Appl. Pol. Sci. 42, 2851 (1991)), in accordance with the following reaction scheme: ##STR3##
This polymer is amorphous and is produced under relatively moderate conditions.
In contrast the commercially available PEEK is produced only at relatively high temperatures and is a highly crystalline, very insoluble material. The production of PEEK is described in U.S. Pat. No. 4,320,224 and is illustrated in the following reaction scheme: ##STR4##
As a result of the aforementioned problems with the polymers synthesized from phenolphthalein by Morgan, such polymers have not been developed commercially.
It has been known for many years that when phenolphthalein reacts with hydroxylamine an intermediate which was thought to be an oxime, forms which on treatment with acid yields 4-aminophenol and 2(4-hydroxybenzoyl)benzoic acid as products (P. Friedlander, Chem. Ber. 26, 172 (1893)). On further treatment of this intermediate with hydroxylamine hydrochloride 4-aminophenol and 4-hydroxyphenyl N-phthalimide are formed. The mechanism of this reaction and the structure of this intermediate was obscure until the work of Lund (H. Lund, Acta Chem. Scand. 14, 359 (1960)) who determined that the intermediate "oxime" was instead the anil of 4-aminophenol with 2-(4-hydroxybenzoyl)benzoic acid.
The reactions described above involving the anil are illustrated in the following reaction scheme: ##STR5##
It has been demonstrated that reaction of 2-(4-hydroxybenzoyl)benzoic acid with phenol produces phenolphthalein and that reaction with substituted phenols gives unsymmetrically substituted phenolphthaleins as products (W. R. Orndorff and R. R. Murry, J. Am. Chem. Soc. 39, 679 (1917)) which would be difficult to prepare by the direct reaction of a phenol with phthalic anhydride. Since it would require separation of unsubstituted, monosubstituted and disubstituted phenolphthaleins.
This reaction is illustrated by the following reaction scheme: ##STR6##